Loans - Narrative, PCI Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable held-for-sale, amount	$ 19,895	$ 0
PCI loans	3,823,238	3,437,085
Purchased Credit-Impaired
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	$ 18,518	$ 17,365
One-to-Four Family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased credit-impaired (PCI) loan percent	22.00%
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased credit-impaired (PCI) loan percent	23.00%	29.00%
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased credit-impaired (PCI) loan percent	40.00%	42.00%